PORTENTS AND PRODIGIES are signs that, if understood or interpreted correctly, can reveal personal destinies and the will of the gods. They may be observed and interpreted either by the person who witnessed them or, more usually, by a priest specializing in the science required.

Portents and prodigies are one of the sources of the art of divination (divinatio in Latin, mantikē technē in Greek). The diviner, who is capable of predicting the future, could have recourse either to the exegesis of observed signs or to prophetic inspiration, a kind of delirium (mania) deriving from his possession by some divinity who comes into contact with diviners, sibyls, or Pythian priestesses.

Some of the words designating portent or prodigy in the languages of classical antiquity (Greek, Latin, and also Etruscan, which remains largely obscure to us) have a clear origin and significance; others have an...